The global energy picture used to be simple. There were producers (oil giants like Saudi Arabia and natural gas titans like Russia), and they sold to consumers (industrial nations like the U.S., China and Germany). It was a precarious situation, one that left consumers vulnerable to high prices and producers at risk of low prices, yet no one expected it to change anytime soon.

But it has, thanks largely to an advanced drilling process that sounds like a network-TV curse word: fracking. The technique, which involves the use of explosives, chemicals and millions of gallons of water to create tiny fractures...